The present invention relates to an air bag apparatus and igniting method thereof, and particularly relates to a two stage-ignition air bag apparatus for a vehicle and igniting method thereof.
Japanese Patent Application Laid-open publication No. 7-47910 discloses a two stage-ignition air bag apparatus for a vehicle.
According to study by the present inventors, there is a structure having two inflators for inflating an air bag as a two stage-ignition air bag apparatus for a vehicle. In such a structure, control for delaying ignition timing of the one inflator after ignition timing of the other inflator is considered to be possible.
More specifically, the air bag apparatus is considered in which control is carried out such that only one inflator is ignited to inflate the air bag by output of generated gas when an extent of collision is small and large gas generating output is not required while the other inflator is also ignited after ignition of the one inflator to inflate the air bag with large gas generating output when the extent of collision is large.
However, in such an air bag apparatus, when the degree of collision is small, only the one inflator is ignited and the other inflator remains unused.
Although a simple structure can be achieved in such an air bag apparatus by forming a single unit from an air bag and the two inflators, the whole unit including the unused inflator is necessary to be replaced after using the air bag apparatus.
In such replacement, it is necessary to eventually dispose of the air bag apparatus detached from a vehicle body. However, because gas generating agent similar to gunpowder remains sealed inside the other unused inflator, additional complicated treatment such as to ask for air bag apparatus disposal specialty service is required.
It is an object of the present invention to provide a two stage-ignition air bag apparatus for a vehicle and igniting method thereof in which disposal of the air bag apparatus after use can be carried out easily.
The two stage-ignition air bag apparatus for the vehicle of the present invention includes an air bag, a first inflator ignited when a value according to collision severity has reached a first threshold value in order to inflate the air bag, and a second inflator ignited at earlier one of times when the value according to collision severity has substantially reached a second threshold value that is greater than the first threshold value and when a predetermined time has passed since the value according to collision severity reached the first threshold value in order to inflate the air bag.
In other words, the two stage-ignition air bag apparatus for the vehicle of the present invention includes the air bag, first gas generating means ignited when the value according to collision severity has reached the first threshold value in order to inflate the air bag, and second gas generating means ignited at earlier one of times when the value according to collision severity has substantially reached the second threshold value that is greater than the first threshold value and when the predetermined time has passed since the value according to collision severity reached the first threshold value in order to inflate the air bag.
On the other hand, a method of igniting the two stage-ignition air bag apparatus for the vehicle of the present invention including the first inflator and the second inflator comprises the steps of igniting the first inflator when the value according to collision severity has reached the first threshold value and igniting the second inflator at earlier one of times when the value according to collision severity has substantially reached the second threshold value that is greater than the first threshold value and when the predetermined time has passed since the value according to collision severity reached the first threshold value.